Automated window treatment control systems provide commands to motor drive units, which actuate window treatments, such as roller shades. U.S. Pat. No. 8,288,981 (the '981 patent) is incorporated by reference herein in its entirety. The '981 patent describes an automated window treatment control system which uses date, time, location and façade orientation information to automatically adjust shade positions to limit the penetration depth of direct sunlight into a room. The system described in the '981 patent can be operated independently of the weather, and does not require information regarding dynamic changes to the lighting environment, due to shadows or clouds.
Light sensors, such as window sensors, can enhance the performance of window treatment control systems by working at the window level to communicate current exterior light conditions to the automated window treatment management system. The addition of light sensors enables the system to respond appropriately, improve occupant comfort, and enhance the system's energy saving potential. The sensor provides the light management system with information to improve natural daylight, available views, and occupant comfort when shadows are cast on buildings as well as when cloudy or bright sunny weather conditions prevail.